Related methods

Given a set of strings, calculate the set of unambiguous abbreviations for
those strings, and return a hash where the keys are all the possible
abbreviations and the values are the full strings. Thus, given input of
“car” and “cone”, the keys pointing to “car” would be “ca”
and “car”, while those pointing to “cone” would be “co”,
“con”, and “cone”.

The optional pattern parameter is a pattern or a string. Only
those input strings matching the pattern, or begging the string, are
considered for inclusion in the output hash